Friday, June 4, 2010

Genetic Genealogy

I love finding genealogy in unexpected places. On one of the non-genealogy blogs I often read, I found this story last week. From Conversion Diary:

A few years ago my family was asked to participate in a study ofHNPCC, a genetic mutation that causes colon cancer. My dad's family is known to carry it, so some researchers who combine genetics with genealogy wanted to get info from us to find out more about how this mutation has spread. Thorough the study we found out that my dad has it (hence his colon cancer 25 years ago); I had a 50/50 chance of inheriting it, but I didn't get it (whew!).
What I found most interesting was the fact that they've traced all cases of HNPCC back to one man who came to America from Hesse, Germany in the early 1700's. All of us who have or have parents who have the HNPCC mutation are related to one another. I've seen the researcher's chart (names omitted) that shows all these thousands of people spread out all over the country, all going back to this one guy. I found that fascinating.


I hesitate to call it a "cool" story - because of the unfortunate genetic propensity to colon cancer in her family - but I think it's amazing that the researchers were able to determine exactly where that mutation first occurred, and in whom it first occurred, not to mention the relationships of all the people he passed it on to! As a family historian, though, I just think it's a shame that the descendancy chart she saw had names omitted!

5 comments:

Lisa Wallen Logsdon said...

This is really interesting! I did not know this was purely genetic. My grandmother had colon cancer and is the only one in the family who has had it (that we know of). How do I find out more about this?

Astrid said...

HNPCC is hereditary. Most colon cancer is not. However, if you suspect you may have a genetic disorder run in your family, you can visit a genetic counselor and be tested for HNPCC mutations. Some criteria to think about is how many people in your family have had cc and how old were they when they were diagnosed. HNPCC will affect generations and will cause cancer under the age of 50 in most cases. If you carry an HNPCC mutation, you have an 80% lifetime risk of developing cancer.

Lisa Wallen Logsdon said...

I see, then I don't suppose we have a cancer genetic disorder as there has been very little cancer in my family, but in reading so many death certificates from my ancestors I suspect other genetic disorders...more heart related. Thank you!

Michelle {Things I Love} said...

I felt compelled to leave a comment because I wrote my thesis on colon cancer, and what's the point of writing a thesis if not to make snobby comments? HNPCC is the name of a genetic disease, not a single mutation. It is a class of colon cancer that arises from inherited mutations. Some people with HNPCC have a mutation in one particular gene, while others with HNPCC can have a mutation in a completely different gene. So when she says "they've traced all cases of HNPCC back to one man ", she really means that they've traced one specific variant of HNPCC (in this case, she is probably referring to a MSH2 mutation*) to one man. Which is still pretty interesting.

(*Source: http://jama.ama-assn.org/cgi/content/full/291/6/718?maxtoshow=&hits=10&RESULTFORMAT=&fulltext=hnpcc&searchid=1&FIRSTINDEX=0&resourcetype=HWCIT)

Genetics is cool!

Katie O. said...

Wow, there are some really smart people reading this!